Hello to everyone on diyAudio 
I've been surfing the forums for a few days now and there seems to be lots of interesting projects and discussions going on here!
Just to introduce myself - I've been in the electronics hobby for some 30 years, building all sorts of gizmos. I am mainly self-taught but somehow drifted into Computing as a career.
On the audio side, I have build several loudspeaker systems - my first original design was a double-chamber reflex using kevlar drivers. My favourites are transmission lines (built from Hi Fi World plans a few years ago) with Audax aerogel drive units. My latest project was a folded exponential horn for FE207's. I had some fun designing and building these, but my wife says they are too big for our small living room
I have a few amplifiers - my first tube design was ECC83/ SE EL34 with all DIY transformers and choke. I was so impressed with the results that I built a couple more: a poor man's interpretation of the Audio Note M7Tube preamp and a low power headphone/speaker amp using ECC83/ PSE 12BH7 (which you can see on the 'Headwize' site).
I have applied a few mods to my Marantz CD52MkII CD player - I beefed up the supply smoothing/decoupling on the audio side and put sockets in place of the filter op-amps so I can try different chips in these positions - I am using the OPA2604 at present (not entirely satisfied yet though). I also added a Kwok Clock 7. So far, so good.
I don't have any particular allegiences regarding Tube, Bipolar or MOSFET but I do admire functional simplicity.
I've been reading good things about MOSFETS (although I have not used them much) and I have some J49/K135 in the junk box so I'm going to experiment with them. Hot favourite plan at the moment is to use a double emitter follower similar to Hiraga's design, driving a MOSFET output stage biased for Class A operation. I'll post an update when I've made some physical progress on this!
I've been surfing the forums for a few days now and there seems to be lots of interesting projects and discussions going on here!
Just to introduce myself - I've been in the electronics hobby for some 30 years, building all sorts of gizmos. I am mainly self-taught but somehow drifted into Computing as a career.
On the audio side, I have build several loudspeaker systems - my first original design was a double-chamber reflex using kevlar drivers. My favourites are transmission lines (built from Hi Fi World plans a few years ago) with Audax aerogel drive units. My latest project was a folded exponential horn for FE207's. I had some fun designing and building these, but my wife says they are too big for our small living room
I have a few amplifiers - my first tube design was ECC83/ SE EL34 with all DIY transformers and choke. I was so impressed with the results that I built a couple more: a poor man's interpretation of the Audio Note M7Tube preamp and a low power headphone/speaker amp using ECC83/ PSE 12BH7 (which you can see on the 'Headwize' site).
I have applied a few mods to my Marantz CD52MkII CD player - I beefed up the supply smoothing/decoupling on the audio side and put sockets in place of the filter op-amps so I can try different chips in these positions - I am using the OPA2604 at present (not entirely satisfied yet though). I also added a Kwok Clock 7. So far, so good.
I don't have any particular allegiences regarding Tube, Bipolar or MOSFET but I do admire functional simplicity.
I've been reading good things about MOSFETS (although I have not used them much) and I have some J49/K135 in the junk box so I'm going to experiment with them. Hot favourite plan at the moment is to use a double emitter follower similar to Hiraga's design, driving a MOSFET output stage biased for Class A operation. I'll post an update when I've made some physical progress on this!
Welcome.
Sounds like you'll fit right in...
Seems many of us have had a sideline in computing... after many years of that i've managed to make it a sideline.
dave
Sounds like you'll fit right in...
Seems many of us have had a sideline in computing... after many years of that i've managed to make it a sideline.
dave
Welcome from another "Bedfordian" - seems like this is hot audio-shire country😉
I'm in "sunny" Leighton Buzzard.
I'm in "sunny" Leighton Buzzard.
Well, that shows how small a place the world is.
I live in Leighton Buzzard too (not so sunny today though).
Thanks also to Dave for the welcome.
Tony.
(Tony and TonyF were already taken
)
I live in Leighton Buzzard too (not so sunny today though).
Thanks also to Dave for the welcome.
Tony.
(Tony and TonyF were already taken
)
Welcome Tony. Do you have pictures of some of your projects you could post? We love to look at others' stuff.
Cal
Cal
U mean the soldering iron in the pix. (Antex 'C' 15W) or transformer iron 
- a company over here used to sell kits for power transfomers in 20VA, 50VA and 100VA sizes - the output transformers were created from 2x100VA kits by creating a larger winding former using the cutting and glueing method!
BTW, the first amp weighs nearly 7 kilos. I generously sized the output transfomers (and was rewarded with deep tight bass) 🙂
- a company over here used to sell kits for power transfomers in 20VA, 50VA and 100VA sizes - the output transformers were created from 2x100VA kits by creating a larger winding former using the cutting and glueing method! BTW, the first amp weighs nearly 7 kilos. I generously sized the output transfomers (and was rewarded with deep tight bass) 🙂
Cal, I just noticed an unused 20VA kit on the shelf similar to those I used for my amps. The E I laminations can be interleaved or stacked, gapped and glued with a magnetically inert spacer (err.. cardboard). I had to use studding to replace the bolts for the first amp's output transformers.
The book is the Coil Design and Construction Manual by B.B. Babani - an excellent all-round guide to DIY coils and transformers for radio, audio and power. As you can see, it has fallen apart due to frequent use!
The book is the Coil Design and Construction Manual by B.B. Babani - an excellent all-round guide to DIY coils and transformers for radio, audio and power. As you can see, it has fallen apart due to frequent use!
Attachments
Dave,
have a look at http://headwize.com/projects/showfile.php?file=frazer_prj.htm - scroll down to Amplifier Circuit Note 8 which describes how I made the transformers for this amp 🙂
I don't have the 12BH7 specs to hand but I did arrive at the impedance ratio of 2k7:8R by empirical means rather than finger-in-the-air!
have a look at http://headwize.com/projects/showfile.php?file=frazer_prj.htm - scroll down to Amplifier Circuit Note 8 which describes how I made the transformers for this amp 🙂
I don't have the 12BH7 specs to hand but I did arrive at the impedance ratio of 2k7:8R by empirical means rather than finger-in-the-air!
Dave,
I haven't used the 6BM8 before (triode/pentode like ECL82) - I found examples of transformers on www.tubehifi.com suggesting 5K primary for both SE and PP operation.
Fow a low power amp like this, using such a transformer may be possible. SE transformers need to be a bit larger due to the magnetising DC current flowing in the primary but in PP transformer each arm of the primary cancels this out. Hardly a problem in this low power amp.
It should also be possible to build a neat PP amp using a couple of ECL82s with the triode sections as preamp and phase splitter.
I think the ECL82 was a popular valve for record player amplifiers or guitar practice amps. There is an interesting example at
http://www.tubebuilder.com/images/schematics/singleended/ecl82_se1.gif
Tony.
I haven't used the 6BM8 before (triode/pentode like ECL82) - I found examples of transformers on www.tubehifi.com suggesting 5K primary for both SE and PP operation.
Fow a low power amp like this, using such a transformer may be possible. SE transformers need to be a bit larger due to the magnetising DC current flowing in the primary but in PP transformer each arm of the primary cancels this out. Hardly a problem in this low power amp.
It should also be possible to build a neat PP amp using a couple of ECL82s with the triode sections as preamp and phase splitter.
I think the ECL82 was a popular valve for record player amplifiers or guitar practice amps. There is an interesting example at
http://www.tubebuilder.com/images/schematics/singleended/ecl82_se1.gif
Tony.
6BM8 = ECL82
Japanese are in particular a big fan of this tube. Here, Gingertube has an interesting PP amp with its big brother the ECL86 and Morse has a nice 6BM8 SE (called The Gnat)
I have quite a few donors for both, some from budget hifis, so a lower power tube would be like an OPT upgrade.
dave
Japanese are in particular a big fan of this tube. Here, Gingertube has an interesting PP amp with its big brother the ECL86 and Morse has a nice 6BM8 SE (called The Gnat)
I have quite a few donors for both, some from budget hifis, so a lower power tube would be like an OPT upgrade.
dave
Dave,
The Gnat looks like a great project 😎 - I like the elegance of simple designs.
The basic circuit could easily be adapted for other tubes too - 2xECL86 or maybe an ECC83 and 2xEL84. The ECL86 pentode is similar to EL84 and was also a common SE audio amplifier in radios and record players.
Tony.
The Gnat looks like a great project 😎 - I like the elegance of simple designs.
The basic circuit could easily be adapted for other tubes too - 2xECL86 or maybe an ECC83 and 2xEL84. The ECL86 pentode is similar to EL84 and was also a common SE audio amplifier in radios and record players.
Tony.
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